00:01
All right, so let's say we have a water wheel that has water falling on it, and we're told that there's about 100 kilograms of water falling on this every second.
00:14
Like this.
00:15
So we want to find the torque exerted by this falling water on the wheel if it has a radius of 2 .45 meters.
00:25
So the torque is really just going to be the weight of the water times the radius.
00:28
So this will be 980 newtons times 2 .45 meters.
00:38
And so this is 2 ,401 newton meters.
00:44
And we're told that for part b, this torque induces an angular acceleration of 0 .593 radians per second.
00:56
So we want to know what is the moment of inertia of the water wheel.
00:59
So the moment of inertia we can write as just the torque divided by the angular acceleration.
01:04
So if you divide that by 0 .593, this will be 4 ,048 .9 kilograms times the square meter.
01:13
And then part c, to increase the rotational inertia of the water wheel...